# ===.() not being called in case statement **URL:** \ **Category:** Rails\ **Created:** [April 4, 2007, 6:35am UTC](https://www.ruby-forum.com/t/not-being-called-in-case-statement/91058 "2007-04-04T06:35:41Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![monki](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/f07891/32.png) [@monki](https://www.ruby-forum.com/u/monki)\ **Post date:** [April 4, 2007, 6:35am UTC](https://www.ruby-forum.com/t/not-being-called-in-case-statement/91058/1 "2007-04-04T06:35:41Z")
I’ve been trying to get the open\_id\_authentication plugin to play nice in my applications, and after a few hours of trial and error I have it running. I had to make a number of changes from the README text, and I’m trying to pin down what is going on with the case statement for status. Here is a simplified version that still exhibits the problem: * * * class Result def self. new(code) end def initialize(code) @code = code end def ===(code) puts ‘===’ @code == code end end result = Result[:successful] case result when :successful puts ‘successful’ else puts ‘unsuccessful’ end * * * # My expected output: successful But the actual output is: unsuccessful My understanding is that case statements use the === function for comparisons. And in some cases they certainly do (I have seen it work on other examples). It would appear that in this case the === is not even being called at all (I tried to pin down what function was being called, but didn’t have much luck). Could somebody please explain to me why this doesn’t work or how one might fix it? ---
**Author:** ![monki](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/f07891/32.png) [@monki](https://www.ruby-forum.com/u/monki)\ **Post date:** [April 4, 2007, 9:56am UTC](https://www.ruby-forum.com/t/not-being-called-in-case-statement/91058/2 "2007-04-04T09:56:45Z")
monki wrote: > ``` > new(code) > > ``` > > ## end > > on other examples). It would appear that in this case the === is not > even being called at all (I tried to pin down what function was being > called, but didn’t have much luck). > > Could somebody please explain to me why this doesn’t work or how one > might fix it? The === function is called on the object in the when condition, with the case object as the parameter, not the other way around. It won’t work with the simplified code you’ve presented, but you’ll probably have to write something like: result = Result[:successful] case result when Result[:successful] then puts ‘successful’ else puts ‘unsuccessful’ end – We develop, watch us RoR, in numbers too big to ignore. ---
**Author:** ![monki](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/f07891/32.png) [@monki](https://www.ruby-forum.com/u/monki)\ **Post date:** [April 4, 2007, 4:38pm UTC](https://www.ruby-forum.com/t/not-being-called-in-case-statement/91058/3 "2007-04-04T16:38:19Z")
> The === function is called on the object in the when condition, with > the case object as the parameter, not the other way around. It won’t > work with the simplified code you’ve presented, but you’ll probably > have to write something like: > That would certainly explain some things, and why it works in the > examples I had seen. > result = Result[:successful] > > case result > when Result[:successful] then puts ‘successful’ > else puts ‘unsuccessful’ > end > I figured it could be done this way, but it seemed wasteful to create > a new object instance just to compare against. Not exactly sure what I want to do with it at present, but this definately makes it much clearer what is going on. Thanks for the insight. ---
**Author:** ![monki](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/f07891/32.png) [@monki](https://www.ruby-forum.com/u/monki)\ **Post date:** [April 4, 2007, 4:53pm UTC](https://www.ruby-forum.com/t/not-being-called-in-case-statement/91058/4 "2007-04-04T16:53:02Z")
monki wrote: > My understanding is that case statements use the === function for > comparisons. And in some cases they certainly do (I have seen it work > on other examples). It would appear that in this case the === is not > even being called at all (I tried to pin down what function was being > called, but didn’t have much luck). > > Could somebody please explain to me why this doesn’t work or how one > might fix it? Can’t do it for the reasons listed above but this looks almost as pretty irb(main):002:0\> class Result irb(main):003:1\> def self. irb(main):004:2\> new(code) irb(main):005:2\> end irb(main):006:1\> def initialize(code) irb(main):007:2\> @code = code irb(main):008:2\> end irb(main):009:1\> def to\_sym irb(main):010:2\> @code irb(main):011:2\> end irb(main):012:1\> end =\> nil irb(main):013:0\> result = Result[:successfull] =\> #\ irb(main):014:0\> case result.to\_sym irb(main):015:1\> when :successfull irb(main):016:1\> puts ‘yay’ irb(main):017:1\> else irb(main):018:1\* puts ‘nay’ irb(main):019:1\> end yay =\> nil ---
**Author:** ![monki](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/f07891/32.png) [@monki](https://www.ruby-forum.com/u/monki)\ **Post date:** [April 4, 2007, 9:25pm UTC](https://www.ruby-forum.com/t/not-being-called-in-case-statement/91058/5 "2007-04-04T21:25:01Z")
In the end I think it makes the most sense to just add an attr\_reader, and do away with the non-working === (even though it would be nice to handle the comparison automagically) * * * class Result attr\_reader :code def self. new(code) end def initialize(code) @code = code end end result = Result[:successful] case result.code when :successful puts ‘successful’ else puts ‘unsuccessful’ end * * * Which, as one might expect, gives you: successful In any event it is quite good to know the order of operations for case. I couldn’t find anything that described the order and it makes a big difference when you are comparing objects of different classes.